1. Field of the Invention
The present invention relates to a multi-component dispensing package, and more particularly to packages for containing viscous components in separated condition and for dispensing such components to be mixed together into a final material such as a polymerizable adhesive.
2. Description of the Prior Art
Various adhesives and the like are multi-component, that is, they require that two or more viscous components be mixed together in correct proportions immediately prior to being applied to the objects to be adhered. As soon as the components are mixed, polymerization begins and the resulting mixture soon sets up and hardens. The components must be stored separately and not come in contact with each other to prevent premature polymerization. Also, the components normally must be preserved from contact with the atmosphere to avoid unwanted chemical changes.
Examples of such adhesives are (1) epoxy resins, which require hardeners such as polyamines, (2) polyisocyanate, which requires a hardener such as polyol, (3) unsaturated elastomers, which require plasticizers, and (4) miscellaneous resins, which require a cross-linker, such as styrene. Such materials often utilize additional components as promoters or accelerators. Among these are peroxides (for polyisocyanates, unsaturated elastomers and miscellaneous resins) and acidic catalysts (for penolic resins.
Epoxy adhesives have come into widespread use during the last few years because of numerous advantages, such as:
1. Extreme strength PA1 2. Non-shrinking, thus filling the voids when parts to be bonded are poorly fitted. PA1 3. Relatively inexpensive
However, with epoxy adhesives it is critical that the components, usually two, be kept separate until shortly before use in order to prevent premature polymerization or "setting". This characteristic poses some problems, especially for occasional use, as in household applications where the time and trouble involved in dispensing correct proportions, mixing, and storing the materials can exceed the value of using epoxy adhesive for small jobs.
For such smaller applications, originally and still generally today two reactive fluid components (usually quite viscous) are marketed as a packaged pair of conventional, capped tubes from which small quantities of each component can be squeezed out and mixed together just before use. For good results, the user needs to estimate and discharge the ingredients in the correct ratio, usually equal parts. Difficulty is encountered by many users in estimating equal parts of the two ingredients.
It is the general experience that this mode of packaging and dispensing the adhesive components is a cumbersome and quite messy practice. Two caps must be removed, two tubes squeezed, two caps replaced, a stirrer located and used, and some means of applying the mixture devised. All too frequently the viscous components later leak or creep out of the two capped tubes and create a sticky mess whenever they are stored.
On the next occasion of use, the problems are even more frustrating because adhering solidified adhesive can interfere with and modify the expelling orifices so as to interfere with estimating proportions.
In recognition of such problems, several more sophisticated packages have been marketed. One of these has two parallel barrels with end nozzles which discharge in the same region. The two barrels are fitted with pistons linked together so that pushing them inward should discharge equal quantities of the components stored in the barrels. These devices are bulky, relatively expensive, and there are various annoying problems in keeping both of the nozzles unplugged and free of hardened materials.
Other packages provide pairs of plastic packets of components, sometimes joined together, and intend that opening and mixing of the contents of a pair of such packages will provide material for one job. This form of packaging is a bit simpler than the capped tubes, or the tubes with ganged pistons, but the amounts of adhesive is fixed, often leading to wastage, and the number of jobs which can be handled is restricted by the packaging.
Another approach offered commercially consists of a package containing a few small plastic trays having one component in the center and the other separated in the outer annulus. A plastic cover is removed from the tray and the two components then mixed with some instrument. Here again, the amounts of adhesive per job and the number of jobs are severely limited according to the package provided.
Besides the current commercial products described above, a number of devices for dispensing multi-part materials such as adhesives have been described in prior patents. For example, U.S. Pat. No. 2,517,027 describes a Collapsable Tube Like Container For Pastes, one version of which has two or more compartments separated by a longitudinal internal partition. An elastic, slitted neck, or necks, is provided which is stated to allow the materials to be squeezed through the slits, with the slits closing after bending and squeezing stress has been relaxed. The problem with such devices is that the elastic orifices are not perfectly sealed so as to be free from creeping and seepage of the contents. Moreover, encrusted reacted materials may obstruct the slitted orifices.
A number of patented dispensers are based essentially on the familiar toothpaste tube configuration, but having compartments for more than one component. Some of these may serve well for materials which are not designed to harden, but present serious problems when used to package polymerizable adhesives. For example, U.S. Pat. No. 3,335,912 describes a multi-compartment tube with a capped orifice. A somewhat similar design providing a movable partition, or interface, is described in U.S. Pat. No. 3,876,111. None of these solve the basic handling and leaking problems described above in using capped tubes to package such products such as two-part adhesives. In addition, such duplex or triplex assemblies suffer from clogging properties, due to interreaction of the components in the multi-orifice zones, whenever ever used with reactive components.
A special compartmented version is described in U.S. Pat. No. 3,239,105. This device requires a clamp instead of a cap as a closure.
Such squeezable, two-compartment assemblies also have the inherent problem that the comparative viscosities of the components and the comparative sizes of the orifices must be precisely adjusted if manual squeezing is to deliver the components in an acceptable ratio.
Some devices, see U.S. Pat. Nos. 3,261,381 and 2,771,724 provide means for mixing the components with the confines of the devices. Unless all of the mixture can be used at once these are wasteful since the unused portion of the mixture will set up and harden inside the device, thus making it possible to use the device only once.